Use a Retina Image for Higher Resolution Displays (Why do we do this?)

Hey guys, just ont he challenge where it states that for higher res displays in order to optimise images for them we should half the widths and heights of our images. I was just wondering WHY do we do this. I know there’ll be a very simple explanation that I just haven’t managed ot get through my thick skull but in my very basic view… wouldn’t we want higher res images for higher res displays?

TLDR: ELI5 why do we want to half the resolution of images for higher res monitors?

The only thing I’m sure of is that making an image half in width and height without altering it in any other way increases its dpi or pixel density if you prefer by four.

What you say is true, for higher resolution screens a higher resolution image is needed (or else we would be using miniature low-resolution backgrounds today).

Maybe it has something to do with the interaction between the display device and the image. I don’t really know.